Thursday, October 7, 2010

Ear infections are
difficult and painful for your dog. But how can you figure out if your dog has
an ear infection, or something more serious? If you suspect your dog has an ear infection, contact
VCA-VRA today.

Signs of an Ear Infection

About twice per week
we are presented with a dog that has rather profound and acute signs of
vestibular disease. These patients usually present a head tilt, often falling
towards the side of the tilt, and occasionally vomiting. Early on, the dog will
have a peculiar "typewriter-like" movement of the eyes which is
called nystagmus. The eyes will move quickly in one direction then drift more
slowly in the other direction and this eye movement will continue over and over
again. Often, we get concerned pet owners that think these signs might be
related to a brain tumor.

About 95% of the time
these dogs have a triad of subtle signs which in combination are pathognomonic
or absolutely diagnostic for ear disease extending beyond the ear drum. The
reason that these cases are presented to us on a referral basis is because this
group of clinical signs is rare in the most common form of ear infection. The
many thousands of dogs that get an ear infection every year have an infection
of their external ear which is technically designated as Otitis Externa. These
dogs will typically shake their heads and paw at their ears and rub their ears
on the ground. Often evidence of an infection is readily appreciated when one
looks into the dog's ear canal unaided.

Issues Associated with Dog Ear Infections

The vestibular signs
described above don't occur until the infection has spread past the ear drum
which is the farthest medial (towards the midline) extent of the external ear
canal.

Virtually all dogs
whose infection has spread further and now have a more striking set of
presenting signs has some if not all of the abnormalities caused by changes in
all three of the nerves noted below:

2)Cranial Nerve VII: Facial Palsy - Decreased
movement of the face on the same side as the affected ear. The dog cannot blink
his eye on that side and frequently his lip hangs down and won't move. Most of
the time the whole ear moves much less on the affected side compared to the
unaffected side.

3)Cervical Sympathetic Palsy also called Horner's
Syndrome (named after Johann Friedrich Horner, the Swiss ophthalmologist who
first described the syndrome in 1869) - the pupil is smaller on the affected
eye, the eye is sunken back slightly making the opening or orbital fissure
smaller, this sign is enhanced because the eyelid droops somewhat.

This triad of signs is
not only pathognomonic or diagnostic for ear disease but in virtually every
case where middle or inner ear disease is suspected, all three of these nerves
are affected. If one doesn't have all three nerves affected, then one should
put disease processes, other than an ear infection, higher on the list of
potential diagnoses.

What is important to
note here is that although many conditions affecting the brain are life
threatening, most ear infections are not. For many years we explained how the
bony sac that is the middle ear or Tympanic Bulla in dogs is a good place for
infection to sit and cause the clinical signs described. Certainly the middle
and inner ear is virtually the only place in the skull where all three nerves
are in proximity to one another. Repeated advanced studies have shown the
middle ears to look perfectly normal in the face of rather severe clinical
signs. Some dogs definitely have severe middle ear infections that are well
documented with advanced studies, but this is usually the exception rather than
the rule. This leaves us to wonder if the adjoining bone, the petrous temporal
bone, might be the source of the infection and the area in which these three
nerves are affected. At the current time the exact pathology has been elusive
and we really can't say more than these dogs have ear disease. Fortunately,
response to therapy is excellent.

Treatments for Canine Ear Infections

Topical medications
alone are adequate to cure these cases about 95% of the time. We particularly
like medications with Dimethyl Sulfoxide (DMSO) in them and have found most of
them safe even when the tympanum (ear drum) is torn. Oral medications seem to
be unnecessary.

If topical medication
does not work, we recommend a thorough inspection of the ear canal and tympanum
and bulla with endoscopy. This is often quite successful at removing much of
the offensive material and increases the chance of a complete recovery.
Unfortunately once the defenses have been breached and an ear infection has
occurred, it is easier for the next infection to occur.

A very successful
preventative approach that we use on dogs who's infection is under control
consists of keeping the ears acidified so that infection is much less likely to
take hold. White vinegar mixed with an equal portion of room-temperature water
placed in both ears without pressure and then massaged 100 times keeps most
infections away. This 50 percent vinegar solution should be used twice per week
for good long-term infection prevention.

If you believe your
dog has an ear infection and is in need of treatment, contact
VCA-VRA today!

1 comment:

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